Sending an identifier of a wireless local area network to enable handoff of a mobile station to the wireless local area network

ABSTRACT

In a wireless communications network, the presence of a wireless local area network in a cell segment is determined. An identifier of the wireless local area network in the cell segment is sent to at least one mobile station in the cell segment to enable the at least one mobile station to hand off to the wireless local area network. Optionally, information identifying geographic boundaries of cell segments and the wireless local area network can be sent to the at least one mobile station.

TECHNICAL FIELD

The present invention relates generally to sending an identifier of awireless local area network to a mobile station to enable handoff to thewireless local area network.

BACKGROUND

Mobile communications systems are made up of a plurality of cells orcell sectors. Each cell or cell sector provides a radio communicationscenter through which a mobile station establishes a call or othercommunications session with another mobile station or a terminalconnected to either a circuit-switched network (e.g., public-switchedtelephone network or PSTN) or a packet-switched data network. Each cellor cell sector includes a base station (or access point) and a basestation controller (or radio network controller) to enablecommunications with mobile stations in the cell or cell sector.

Wireless networks are capable of carrying both circuit-switched andpacket-switched traffic (e.g., voice traffic, data traffic, etc.).Examples of wireless networks that support communication ofpacket-switched traffic include those that operate according to the CDMA2000 family of standards. The first phase of CDMA 2000 is referred to as1xRTT (also referred to as 3G1X or 1X), which is designed to increasevoice capacity as well as to support data transmission speeds that arefaster than typically available. In addition, for even higher datarates, a 1xEV-DO wireless technology has been developed, defined asTIA/EIA/IS-856, “CDMA 2000, High Rate Packet Data Air InterfaceSpecification,” which is adopted by the TIA. 1xEV-DO provides relativelyhigh data transfer rates over the air interface between mobile stationsand base stations.

Recently, there has been an increase in the use of enterprise andresidential wireless local area networks (WLANs). A WLAN refers to alocal area network that mobile stations can access wirelessly. A WLAN isa private network, either owned by an organization or municipality(enterprise) or by an individual. A WLAN is usually secured such thatonly authorized users are allowed to use the WLAN. A WLAN differs from apublic cellular wireless network in that the WLAN is limited for use byusers of a specific enterprise or a group, whereas the public cellularwireless network is for general use of subscribers of the cellularwireless network. Examples of standards that define WLANs include IEEE(Institute of Electrical and Electronic Engineers) 802.11, 802.11a,802.11b, 802.11g, Bluetooth, WiMAX (Worldwide Interoperability forMicrowave Access), 802.16, and so forth.

Conventionally, mechanisms have not been provided to enable efficienthandoffs from a public cellular wireless network, such as a CDMA 2000network, to a WLAN, since the cellular wireless network and WLAN operateaccording to different technologies.

SUMMARY

In general, a method and apparatus for use in a wireless communicationsnetwork includes determining presence of a wireless local area networkin a cell segment, and sending an identifier of the wireless local areanetwork in the cell segment to at least one mobile station in the cellsegment to enable the at least one mobile station to hand off to thewireless local area network.

Optionally, according to some embodiments, information identifyinggeographic boundaries of cell segments and the wireless local areanetwork can be sent to the at least one mobile station.

Other or alternative features will become apparent from the followingdescription, from the drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example wireless communications networkthat includes a public cellular wireless network and wireless local areanetworks (WLANs).

FIG. 2 is a message flow diagram of a process of performing idle modehandoff from the public cellular wireless network to a WLAN, accordingto an embodiment.

FIG. 3 is a message flow diagram of a process of performing active modehandoff from a public cellular wireless network to a WLAN, according toan embodiment.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments may be possible.

Referring to FIG. 1, an example wireless communications network 10includes components that operate according to a public cellular wirelessprotocol, such as a CDMA (code-division multiple access) 2000 protocol.CDMA 2000 is defined by the CDMA 2000 family of standards (collectivelyreferred to as the IS-2000 Standard, which is developed by the ThirdGeneration Partnership Project 2 (3GPP2)). The CDMA 2000 components ofthe wireless network 10 can include 1xRTT components, 1xEV-DOcomponents, 1xEV-DV components, and/or other components. In otherembodiments, other types of public cellular wireless protocols, such asGSM (Global System for Mobile) and UMTS (Universal MobileTelecommunications System) protocols, can be used for communications inthe wireless communications network 10. A “public cellular wirelessprotocol” or “public wireless protocol” defines a wireless network thatis generally available to any subscriber of the wireless network.

Optionally, for circuit-switched communications, the wirelesscommunications network 10 includes a mobile switching center (MSC) 32which is responsible for switching mobile station-originated or mobilestation-terminated circuit-switched traffic. Effectively, the MSC 32 isthe interface for signaling and user traffic between the wirelessnetwork 10 and other public-switched networks (such as a public-switchedtelephone network (PSTN) 34 or other MSCs).

The wireless communications network 10 includes cell segments 12, eachassociated with a radio network controller (RNC) 14 or base stationcontroller (BSC). A “cell segment” refers to either a cell or cellsector. Typically, in the CDMA 2000 context, a BSC is used in a 1xRTTnetwork, while an RNC is used in a 1xEV-DO or 1xEV-DV network. In thisdiscussion, the term “radio network controller” or “RNC” refers to a1xEV-DO or 1xEV-DV RNC, a 1xRTT BSC, or any other type of radio networkcontroller or base station controller. Each RNC 14 is connected to anaccess point 20 (sometimes referred to as a base station transceiver).The access point 20 is an entity used for radio frequency (RF)communications with mobile stations within a cell segment 12.

The RNC 14 supports packet-switched communications, in which packet datais communicated between a mobile station and another endpoint, which canbe a terminal coupled to a data network 16 or another mobile stationthat is capable of communicating packet data. Examples of the datanetwork 16 include private networks (such as local area networks or widearea networks) and public networks (such as the Internet). In oneexample, the RNC 14 supports packet data services through a packet dataserving node (PDSN) 18.

In some embodiments, packet-switched communications are defined by theInternet Protocol (IP). In packet-switched communications (e.g.,electronic mail, web browsing, electronic gaming, voice-over-IP, etc.),packets or other units of data carry payload (including user data) aswell as header information including routing information (in the form ofaddresses) used for routing the packets or data units over one or morepaths of the network to a destination endpoint. IP defines a type ofconnectionless, packet-switched communications. One version of IP,referred to as IPv4, is described in Request for Comments (RFC) 791,entitled “Internet Protocol”, dated September 1981; and another versionof IP, referred to as IPv6, is described in RFC 2460, entitled “InternetProtocol, Version 6 (IPv6) Specification”, dated December 1998.

The RNC 14 includes a controller 22 (to perform various tasks) andstorage 24 (to store data). The RNC 14 also includes an interface 23 forcommunicating with mobile stations over wireless links (through therespective access point 20). Mobile stations 26 each also include acontroller 28 (to perform various tasks) and a storage 30 (to storedata). Examples of mobile stations 26 include mobile telephone handsets,portable computers, personal digital assistants, and so forth.

The RNC 14 is coupled to the PDSN 18 through a data network, such as anR-P (Radio Packet) transport network, to enable packet-switchedcommunications with the packet-switched data network 16. An R-Ptransport network (or interface) supports establishment of an R-Psession, which is a logical connection between the RNC and the PDSN fora particular PPP (Point-to-Point Protocol) session. PPP is described inRFC 1661, entitled “The Point-to-Point Protocol (PPP),” dated July 1994.During a communications session, packet data is routed between a mobilestation 26 and another endpoint through an RNC 14, R-P transportnetwork, and PDSN 30.

In the example arrangement of FIG. 1, two wireless local area networks(WLANs) 36 and 38 are depicted as being inside a cell segment 12. Notethat in alternative arrangements, a cell segment 12 can include just oneWLAN, no WLAN, or more than two WLANs. A WLAN operates according to adifferent wireless technology than the public cellular wireless networkprovided by the RNCs 14 in cell segments 12. As examples, protocols thatdefine WLANs include IEEE 802.11, IEEE 802.11a, IEEE 802.11b, IEEE802.11g, IEEE 802.16, WiMAX, and so forth.

In accordance with some embodiments, the RNCs 14 of the public cellularwireless network and base stations 40, 42 of the WLANs 36, 38 areconfigured to enable handoffs between cell segments 12 of the publiccellular wireless network and the WLAN 36 or 38. The ability toseamlessly hand off a mobile station between a cell segment and a WLANenables authorized users of the WLAN to start communicating in the WLANwhere the users may have access to expanded services and data providedby the WLAN, and/or more advantageous billing arrangements. For example,a user engaged in a voice-over-IP call in the public cellular wirelessnetwork can hand off to a WLAN, where the user can continue thevoice-over-IP call without interruption. The handoff between the publiccellular wireless network and a WLAN can also occur while the user isinvolved in another type of packet-switched communications (e.g., webbrowsing, electronic mail, electronic gaming, etc.).

The WLAN 36 includes one or more multiple base stations (or accesspoints) 40, and the WLAN 38 similarly includes one or multiple basestations (or access points) 42. Generally, the base stations thatoperate within a WLAN have a shorter range than the access points 20associated with cell segments 12. The WLAN can be associated with anenterprise or with a particular group or residence. Unlike in a publiccellular wireless network where any subscriber has access to thecellular wireless network, a WLAN allows only authorized mobile stationsto operate within the WLAN. For example, the first WLAN 36 may belong toCompany X, while the second WLAN 38 may belong to Company Y. Thus,mobile stations of employees of Company X can operate in WLAN 36 but notin WLAN 38, while mobile stations of employees of Company Y can operatein WLAN 38 but not in WLAN 36. Note that employees of either Company Xor Y that are subscribers of the public cellular wireless network areable to operate in the cell segments 12.

In accordance with some embodiments, to enable handoffs between an RNC14 and a base station in a WLAN, a predetermined message or aninformation field of an existing message is defined to communicateidentifier(s) of WLAN(s) within a cell segment 12 to mobile stationssuch that the mobile stations are aware of the presence of the WLAN(s).For example, an identifier of a WLAN can be communicated to mobilestations in a broadcast message, such as a message in a broadcastcontrol channel (BCCH). Alternatively, the identifier of a WLAN can becommunicated in a neighbor list to a specific mobile station. In otherembodiments, other messages or information fields for communicating theidentifier of a WLAN can also be used.

According to some embodiments, to enhance security, the identifier of aWLAN that is communicated from an RNC 14 to a mobile station 26 is a“private” identifier, which is different from a service set identifier(SSID) of the WLAN. Communicating the private identifier reduces theoccurrence of communicating SSIDs in un-secured messages between an RNCand a mobile station. Communicating an SSID of a WLAN, such as sendingthe SSID in a broadcast message, poses a security risk in that hackersmay obtain such an SSID to hack into a WLAN. Note that a WLAN istypically a secure network in which only authorized users are able tocommunicate. Allowing a hacker to gain access to a WLAN would thus beundesirable.

As described in further detail below, two types of handoffs are providedby a mechanism according to some embodiments. A first type of handoff isan idle mode handoff, in which handoff is performed between an RNC and aWLAN while the mobile station is not actively communicating traffic(data, voice, etc.). The mobile station is considered to be idle when itis not actively in a call session. The other type of handoff is theactive mode handoff, in which handoff occurs between an RNC and a WLANwhile the mobile station is active in a call session.

Idle mode handoff is performed by communicating private identifier(s) ofWLAN(s) in a cell segment to the mobile stations in a broadcast message(e.g., BCCH). The broadcast of private identifier(s) of WLAN(s) allowsnotification of available WLANs within a cell segment 12 to mobilestations in the cell segment 12.

To perform active mode handoff, the private identifier(s) of WLAN(s)that a particular mobile station is authorized to use is (are)communicated to the particular mobile station in a neighbor list (e.g.,in a NeighborList message). The NeighborList message identifiesneighboring cell segments 12 as well as WLANs that a mobile station isable to hand off to. In accordance with some embodiments, theNeighborList message contains special fields that contain identifiers ofWLAN(s). According to some embodiments, a first NeighborList messagesent to a first mobile station in a given cell segment 12 can containdifferent neighbors (such as different WLANs) than a second NeighborListmessage sent to a second mobile station in the given cell segment 12.

For example, the first NeighborList message can identify WLAN 36 but notWLAN 38 to the first mobile station, and the second NeighborList messagecan identify WLAN 38 but not WLAN 36 to the second mobile station. Inanother example, the first NeighborList message can identify one or bothof WLANs 36, 38, while the second NeighborList message does not identifyany WLAN. By not including an identifier of a particular WLAN in aneighbor list sent to a mobile station that the mobile station is notauthorized to use, the mobile station would not have to waste resources(e.g., battery power, air interface bandwidth, etc.) scanning for theparticular WLAN to find out that the mobile station in fact is notauthorized to use the particular WLAN.

A benefit of communicating identifiers of WLANs that are present in acell segment 12 (such as either in a broadcast message or in a neighborlist) is that mobile stations in the cell segment 12 are explicitlynotified of the presence of the WLANs. As a result, the mobile stationsin the cell segment 12 would not have to waste resources scanning forWLANs that may or may not be present. Also, by explicitly communicatingidentifiers of available WLANs, it is ensured that the mobile stationsare notified of the presence of WLANs such that the mobile stations willbe able to hand off to appropriate WLANs to take advantage of additionalfeatures offered by some WLANs to authorized users.

FIG. 2 is a message flow diagram of a process of performing idle modehandoff in a particular cell segment 12. The RNC 14 supporting theparticular cell segment 12 identifies (at 102) WLAN(s) in its cellsegment. The identification of WLAN(s) is based on information providedto the RNC by the network operator. Information identifying the WLAN(s)in the cell segment 12 is stored in the storage 24 (FIG. 1) of the RNC14. The RNC 14 also stores (at 104) information mapping privateidentifier(s) to SSID(s) of respective WLAN(s). A network operator candefine proprietary mappings between private identifiers and SSIDs insome implementations.

A message is then sent (at 106) from the RNC 14 to a mobile station 26.Note that the message sent at 106 can also be sent to additional mobilestation(s) in the cell segment 12. The message sent at 106 includespreference information regarding the preferred WLAN or WLANs of themobile station, as well as the mapping information that maps betweenprivate ID(s) and SSID(s) for WLAN(s) in the cell segment 12. Forsecurity, the message sent at 106 can be encrypted or protected by someother technique to prevent unauthorized access of the mapping betweenprivate ID(s) and SSID(s).

The preference information is used by the mobile station to select thepreferred WLAN from among plural WLANs. For example, a mobile stationmay be authorized to use more than one WLAN in a particular cellsegment. One of the WLANs would be the preferred WLAN for the mobilestation. In other embodiments, preference information is not sent fromthe RNC to the mobile station. In response to the message sent at 106,the mobile station stores (at 108) the preference information and themapping information (such as in the storage 30 (FIG. 1) of the mobilestation.

For idle mode handoff, the RNC 14 sends (at 110) a broadcast message(e.g., BCCH) containing the private identifier(s) of the WLAN(s) in thecell segment 12. A broadcast message is received by all mobile stationsin the cell segment 12. Predefined information fields in the BCCH areused to carry the private identifiers. Alternatively, a differentmessage can be defined to carry the private identifiers. Instead ofcommunicating the private identifiers of WLANs in a cell segment in abroadcast message sent to multiple mobile stations in a cell segment 12,the private identifiers of WLANs can be sent in a message targeted to anindividual mobile station.

In response to receiving the private identifier(s) from the RNC, themobile station scans (at 112) for the preferred WLAN from among theidentified WLANs, based on the stored preference information discussedabove. Based on scanning for the preferred WLAN, the mobile stationacquires (at 114) the WLAN control channels to perform the idle modehandoff from the RNC to a base station of the WLAN, such that the mobilestation can subsequently communicate with the base station of the WLANinstead of with the RNC.

Note that similar techniques are employed to perform idle mode handofffrom a WLAN to a cell segment.

FIG. 3 shows a message flow diagram for active mode handoff. Note thattasks 102 and 104 of FIG. 2 have already been performed prior to thestart of FIG. 3, and that a cell call session has been established (at202) between the RNC and mobile station. A cell call session refers to acall session established in the cellular wireless network.

The RNC determines (at 204) if a WLAN exists in the cell segment. If aWLAN does not exist in the cell segment, then the RNC creates (at 206) ageneric neighbor list. A generic neighbor list is a neighbor list thatidentifies other cell segments as neighbors, but that does not identifya WLAN as a candidate neighbor to which a mobile station can hand off.

If the cell segment does contain one or more WLANs, the RNC determines(at 208) whether the mobile station is authorized to use any of theWLAN(s). If not, then the generic neighbor list is created (at 206).However, if the mobile station is authorized to use any of the WLAN(s),then the RNC creates (at 210) a neighbor list that contains WLANidentifier(s) (that the mobile station is authorized to use) as well asidentifiers of neighboring cell segments 12.

The RNC sends (at 212) a NeighborList message to the mobile station,where the NeighborList message contains the neighbor list created at 206or 210. Assuming that a WLAN is present that the mobile station isauthorized to use, the mobile station then determines (at 214) whetherthe mobile station is within range of the WLAN. If so, the mobilestation sends a handoff request (at 216) to the RNC. The RNC thenperforms a handoff procedure (at 218) with the base station of the WLAN.A handoff direction message is then sent (at 220) to the mobile stationto direct the mobile station to hand off to the base station of theWLAN. Next, a WLAN session is established (at 222) between the mobilestation and the base station of the WLAN to continue the communicationof traffic in the WLAN instead of in the cell segment.

Similar techniques are employed to perform active mode handoff from aWLAN to a cell segment.

The determination of whether a mobile station is within the range of aWLAN (performed at 214) can be accomplished in one of a number ofdifferent ways. One technique is based on radio frequency (RF) signalmeasurements, such as RSSI (RF signal strength), C/I (RF signalquality), or RTD (roundtrip delay). However, performing handoff based onmeasurements of RF signals may not be efficient in some scenarios due tothe likelihood of a rapid succession of handoffs (ping-pong handoffs)between two different cell segments or a cell segment and a WLAN at aboundary between the two cell segments or a cell segment and a WLAN.

In an alternative embodiment, instead of basing handoff on measurementsof RF signals, a location-based handoff technique is used. Thelocation-based handoff technique involves defining specific (which canbe fixed) geographic boundaries between cell segments as well asboundaries of a WLAN within a cell segment. Such information defininggeographic boundaries of cell segments and WLANs is communicated by RNCsto a mobile station when the mobile station is located within respectivecell segments. A mobile station is able to acquire information relatingto its location, and based on this acquired location, determine whethera handoff is appropriate. For example, the mobile station can include aglobal positioning system (GPS) receiver to establish its location basedon GPS coordinates. Alternatively, the location of the mobile stationcan be based on triangulation based on signals from three differentaccess points in three cell segments. Based on the determined locationof the mobile station, the mobile station or RNC (as appropriate) canmake a decision regarding whether handoff to a WLAN or to a differentcell segment is desirable.

Defining the boundaries of the cell segments and WLANs can beaccomplished by performing RF propagation analysis where the networkoperator performs measurements with an access point or base station in acell segment or WLAN to determine the appropriate boundaries. Once thegeographic boundaries are ascertained, the information identifyingboundaries are communicated to mobile stations for storage in the mobilestations. Based on determined geographic locations of the mobilestations, the mobile stations will be able to determine whether handoffto another cell segment or WLAN is appropriate. Alternatively, theinformation identifying boundaries is not communicated to mobilestations, but rather, is maintained in an RNC or WLAN base station.Based on the geographic location of a mobile station, the RNC or WLANbase station can then determine whether handoff is desirable (orpermitted). To avoid the issue of ping-pong handoffs between two cellsegments or between a cell segment and a WLAN, hysteresis can be definedfor the boundaries.

Instructions of the various software modules (e.g., software modulesexecuted in the RNCs 14, WLAN base stations 40, 42, or mobile stations26) are loaded for execution on corresponding processors. Processorsinclude microprocessors, microcontrollers, processor modules orsubsystems (including one or more microprocessors or microcontrollers),or other control or computing devices. As used here, a “controller” or“control module” refers to hardware, software, or a combination thereof.A “controller” or “control module” can refer to a single component or toplural components (whether software or hardware).

Data and instructions (of the software) are stored in respective storagedevices, which are implemented as one or more machine-readable storagemedia. The storage media include different forms of memory includingsemiconductor memory devices such as dynamic or static random accessmemories (DRAMs or SRAMs), erasable and programmable read-only memories(EPROMs), electrically erasable and programmable read-only memories(EEPROMs) and flash memories; magnetic disks such as fixed, floppy andremovable disks; other magnetic media including tape; and optical mediasuch as compact disks (CDs) or digital video disks (DVDs).

The instructions of the software are loaded or transported to eachentity in one of many different ways. For example, code segmentsincluding instructions stored on floppy disks, CD or DVD media, a harddisk, or transported through a network interface card, modem, or otherinterface device are loaded into the entity and executed ascorresponding software routines or modules. In the loading or transportprocess, data signals that are embodied in carrier waves (transmittedover telephone lines, network lines, wireless links, cables, and thelike) communicate the code segments, including instructions, to theentity. Such carrier waves are in the form of electrical, optical,acoustical, electromagnetic, or other types of signals.

While some embodiments have been disclosed with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations there from. It is intended that theappended claims cover such modifications and variations as fall withinthe true spirit and scope of the invention.

1. A method for use in a wireless communications network, comprising:determining presence of a wireless local area network in a cell segment;and sending an identifier of the wireless local area network in the cellsegment to at least one mobile station in the cell segment to enable theat least one mobile station to hand off to the wireless local areanetwork.
 2. The method of claim 1, wherein sending the identifiercomprises sending the identifier from a radio network controller.
 3. Themethod of claim 1, wherein sending the identifier comprises sending theidentifier in at least one of a broadcast control channel and a neighborlist.
 4. The method of claim 3, wherein sending the identifier in thebroadcast control channel enables idle mode handoff from the cellsegment to the wireless local area network.
 5. The method of claim 3,wherein sending the identifier in the neighbor list enables active modehandoff.
 6. The method of claim 1, further comprising: determiningpresence of at least a second wireless local area network in the cellsegment; and sending identifiers of respective wireless local areanetworks to plural mobile stations in the cell segment.
 7. The method ofclaim 1, further comprising: determining presence of at least a secondwireless local area network in the cell segment; and determining whichof the first and second wireless local area networks the at least onemobile station is authorized to use, wherein sending the identifier tothe at least one mobile station comprises sending the identifier of theone of the first and second wireless local area networks the at leastone mobile station is authorized to use.
 8. The method of claim 1,wherein sending the identifier to the at least one mobile stationcomprises sending the identifier in a first neighbor list, the methodfurther comprising: sending a second neighbor list to a second mobilestation, the second neighbor list not including the identifier of thewireless area network.
 9. The method of claim 1, wherein determiningpresence of a wireless local area network comprises determining presenceof a wireless local area network that operates according to a firstprotocol different from a second protocol of the cell segment.
 10. Themethod of claim 1, further comprising sending information identifyinggeographic boundaries of cell segments and the wireless local areanetwork to the at least one mobile station.
 11. The method of claim 10,further comprising receiving a request to hand off based on a locationof the at least one mobile station determined by the at least one mobilestation and based on the information identifying the geographicboundaries.
 12. An article comprising at least one storage mediumcontaining instructions that when executed cause a system to: determinepresence of a wireless local area network in a cell segment; send anidentifier of the wireless local area network to a mobile station toenable handoff of the mobile station from the cell segment to thewireless local area network.
 13. The article of claim 12, wherein theinstructions when executed cause the system to further: determinewhether the mobile station in the cell segment is authorized to use thewireless local area network; wherein sending the identifier of thewireless local area network is in response to determining that themobile station is authorized to use the wireless local area network. 14.The article of claim 12, wherein the instructions when executed causethe system to further: store a mapping between a private identifier anda service set identifier (SSID) of the wireless local area network,wherein sending the identifier to the mobile station comprises sendingthe private identifier instead of the SSID.
 15. The article of claim 12,wherein the instructions when executed cause the system to further: handoff the mobile station from a radio network controller of the cellsegment to a base station of the wireless local area network, the radionetwork controller operating according to a public cellular wirelessprotocol, and the base station operating according to a protocol of adifferent type from the public cellular wireless protocol.
 16. Thearticle of claim 12, wherein the instructions when executed cause thesystem to further send information identifying geographic boundaries ofcell segments and the wireless local area network to the at least onemobile station.
 17. A system comprising: an interface to a wireless linkfor communicating with a plurality of mobile stations; and a controlmodule operable to: send first messaging to a first one of the mobilestations, the first messaging identifying a first set of neighbors towhich the first mobile station is able to hand off, and send secondmessaging to a second one of the mobile stations, the second messagingidentifying a second, different set of neighbors to which the secondmobile station is able to hand off.
 18. The system of claim 17,comprising a radio network controller for managing communications in afirst area according to a first technology, the control module beingpart of the radio network controller, wherein the first set of neighborscomprises a base station for wireless communications in a second areaaccording to a second, different technology, and wherein the second setof neighbors does not include the base station.
 19. The system of claim18, wherein the first technology is defined by a public cellularwireless network protocol, and the second technology is defined by asecond, different wireless protocol.
 20. The system of claim 19, whereinthe public cellular wireless network protocol comprises one of acode-division multiple access (CDMA) protocol, a Global System forMobile (GSM) protocol, and a Universal Mobile Telecommunications System(UMTS) protocol.
 21. The system of claim 18, wherein the second area iswithin the first area.